Design, Fabrication of Equal Channel Angular Extrusion Process and its Effect on Microstructure and Hardness of Al and Cu Alloys

Abstract

Equal channel angular extrusion (ECAE) is considered as an advanced extrusion process, where metal billets are plastically deformed without reducing its cross-sectional area. In this study, a die was designed and fabricated with channel angle and diameter of 110° and 12.44 mm, respectively, for extruding aluminum and copper alloys via ECAE process. The die and punches were made from EN-31 steel and were heat-treated to achieve hardness of 45 HRC. The heat treatment cycle for the die and punch consisted of austenitizing them at 840 °C for 1.5 h, followed by quenching in oil to form martensite, and tempering at 450 °C for 1 h, followed by air cooling to room temperature. The inner surface of channel in the die was electroplated with hard chrome. Aluminum and copper alloys were successfully extruded by ECAE process at room temperature. Aluminum and brass samples were subjected to single pass, whereas copper sample was subjected to double pass during ECAE processing. Microstructures of ECAE-processed aluminum and copper samples were examined under optical microscope, and hardness was measured. Microstructural examination shows significant grain refinement in ECAE-processed samples as compared to as-received billets. The hardness of ECAE-processed samples was significantly greater than that of as-received billet.